Abstract
Circadian rhythms are synchronized by the external environment and are responsible for regulating many of physiological processes in organisms. In plants, a key component in the regulation of these physiological processes is referred to as circadian resonance (CR), which maximizes plant growth by entraining the periodicity of plant circadian rhythms to the external light-dark cycle. However, CR has only been extensively studied in Arabidopsis thaliana, and it is not known whether CR has a similar function in other plant species. In addition, the potential for manipulating CR in order to maximize agricultural production or plant growth has not yet been investigated. In this study, we sought to characterize the occurrence and role of CR in lettuce (Lactuca sativa L.), which is widely cultivated in closed plant factories. Our results showed that the variation in aerial weight is dependent upon both cultivar type and light quality, and the efficiency of CR is highest under red LED illumination and lowest under fluorescent light illumination. Furthermore, we demonstrated that LEDs may be highly beneficial for maximizing plant growth. Compared to FL illumination, LED illumination can be used to precisely control the circadian rhythm of plants and increase cultivation efficiency.
